A steam turbine installation is in particular used in a thermal power plant for generating electrical energy. It is desirable, in particular for ecological and economic reasons, for the steam turbine installation to be operated at as high a thermal efficiency as possible. It is conventional for the steam turbine installation to have a steam turbine and a steam generator which heats feed water and thus produces live steam which is made available to the steam turbine for driving same. This cyclic process of the steam turbine installation is configured, as is conventional, such that it is at maximum thermal efficiency when the steam turbine is under full load. Other operating states, below full load, lead to correspondingly lower thermal efficiencies.
However, partial-load operation of the steam turbine installation, especially when the latter is used in the power plant, is highly relevant as, for example in the case of the steam turbine installation, a power reserve must be maintained in order to cope with overload operation states. It is thus desirable to operate the steam turbine installation over a broad load range with a thermal efficiency that is as high as possible.